Hydraulic valve detent mechanism

ABSTRACT

A hydraulic valve having a detent mechanism engaging the valve to releasably retain the valve in an open position and hydraulically release the valve to automatically return to a normally neutral position in response to a predetermined pressure in the system.

O United States Patent 1111 3,568,717

[72] Inventors John R. Plate; [56] References Cited George A. Van Den Heuvel, Milwaukee, rr STATES PATENTS James McBumetist" Wat", 2,536,141 1/1951 Rockwell 251/73 Okla- 2,689,585 9/1954 Presnell 137/624.27 [21] App]. No. 858,035 2,848,014 8/1958 Tennis l37/624.27 [221 PM Sew-1511969 3,132,668 /1964 Stacey.... 137/624.27 Pat?med Mai-911971 3,465,649 9/1969 Eggers l37/624.27 [73] Assignee Allis-Chalmers Manufacturing Company Milwaukee, w Primary Examiner-Wilham F. ODea Assistant Examiner-William H. Wright Att0meysArthur L. Nelson, Kenneth C. McKivett and 541 HYDRAULIC VALVE DETENT MECHANISM RObe" 10 Claims, 4 Drawing Figs.

[52] U.S.Cl l37/624.27 ABSTRACT: A hydraulic valve having a detent mechanism 1 [51] lnt.Cl. ..Fb 15/26, engaging the valve to releasably retain the valve in an open F16k /00 position and hydraulically release the valve to automatically Field of Search l37/624.27; return to a normally neutral position in response to a predetermined pressure in the system.

HYDRAUJMC VALVE DETENT MEQHANKSM This invention relates to a hydraulic valve and more particularly to a detent mechanism which mechanically holds a valve in a predetermined open position and hydraulically releases the valve in response to a predetermined pressure in a hydraulic system to permit the valve to return to a normally neutral position.

The conventional hydraulic system on tractors employs a source of pressurized fluid and a hydraulic valve in the system to control the flow of pressurized fluid to a hydraulic actuator to perform the function desired such as an implement lift. At the convenience to the operator the valve should include a means for retaining the valve in the open position until the hydraulic actuator completes the cycle of operation. Accordingly, when the cycle of the hydraulic actuator is completed the pressure increases in the system and the pressure can be used to release the valve which then automatically returns to its normally neutral position.

Accordingly this invention includes a hydraulic valve as illustrated to control a double action hydraulic actuator. The same principle could be used to control a single action hydraulic actuator. Actuation of either side of the actuator is substantially similar and is controlled manually through the valve. As the hydraulic control valve is openeda mechanical detent mechanism engages the spool of the valve to retain the valve in the open position even though the actuating lever is released by the operator. Subsequent to opening of the valve and engagement of the detent mechanism, the hydraulic fluid passes through the valve to the hydraulic actuator to perform the hydraulic function. When the hydraulic actuator cycle is complete, the pressure builds up in the system which in turn is directed through a poppet valve in the control valve spool. The pressure buildup in the poppet valve chamber unseats detents which release the spring biased spool to a normally neutral position. The release of the detents is hydraulic and operates against a spring biased detent mechanism to allow the control valve to close when the cycle is complete. The reverse operation of the control valve to return the hydraulic actuator in the return cycle is similar to that just described. The detent mechanism operates in a different set of detent grooves and when the pressure in the system builds up to maximum the detent mechanism is again hydraulically released and the hydraulic control valve returns to a normally neutral position. The valve will operate is an open center or closed center system.

it is an object of this invention to provide a detent mechanism for a hydraulic control valve.

it is another object of this invention to provide a detent mechanism for a hydraulic control valve which mechanically engages upon actuation, and hydraulically disengages the control valve upon completion of the cycling of a hydraulic actualot.

it is a further object of this invention to provide a detent mechanism for releasably retaining a hydraulic control valve in a predetermined open position permitting a hydraulic actuator to perform its cycle and automatically release the spool of the valve in response to pressure buildup in the hydraulic system to permit the spool of the control valve to return to a normally neutral position.

it is a further object of this invention to provide a hydraulic control valve having a plurality of operating positions defined by mechanically actuated detents engaging the hydraulic valve spool and hydraulic means to release the detent mechanism in response to a predetermined pressure buildup in the valve when the hydraulic cycle is complete.

The objects of this invention are accomplished by providing a hydraulic control valve for controlling the flow of pressurized fluid from a source of pressurized fluid to a hydraulic actuator. The control valve is manually operated to initiate the flow of pressurized fluid through the valve and is retained in the open position by a detent mechanism engaging the spool of the valve. The spool is selectively retained in one of a plurality of operating positions defined by grooves in the spool of the valve which are engaged by a mechanically operated mechanism. The hydraulic fluid flows through the control valve to the actuator until the cycle is complete at which point the pressure builds up and opens a poppet valve at a predetermined pressure above the operating pressure of the system permitting the flow of pressurized fluid into the poppet valve chamber which in turn is in communication with one side of the detents. The increased pressure in the poppet valve chamber unseats the detents permitting the spring biased spool to return to a normally neutral position and a closed condition of a hydraulic valve. The valve is provided with manual lever connected to the spool for initiating the flow of pressurized fluid and an automatic detent mechanism to maintain the control valve in this position until the cycle is complete.

The valve provides a plurality of operating positions and the hydraulic means to release the valve to return to a normally neutral position in response to pressure buildup in the system. Adjustable means are provided to control the pressure of operation of the poppet valve.

The invention is illustrated in the attached drawings.

FIG. 1 illustrates the hydraulic control valve and the detent mechanism in a normally neutral position.

FIG. 2 illustrates the valve spool of the hydraulic control valve in thelower position with the detent mechanism maintaining the valve position.

FIG. 3 illustrates the detent mechanism in the lower position and the detent mechanism in the corresponding lift detent grooves.

FIG. 4 illustrates the hydraulic control valve in the float position and the detents in the float grooves.

Referring to the drawings FIG. 1 shows the control valve 1 which controls the flow of pressurized fluid from the pump 2 to the hydraulic actuator 3. The control valve 1 includes a spool 4 manually operated by lever 5 for reciprocal movement within the valve housing 6. Although only a lever is illustrated other suitable means may be used to operate the spool manually or automatically. The spool 4 extends through the housing into the casing 7. for the detent mechanism which is held on the end of the housing 6 by means of a plurality bolts 8. The bolts 8 also fasten a cup 9 which encloses the return spring 10.

The spring 10 in the cup 9 is seated on the spring retainers ll and 12 which are supported on the bolt 13 which in turn threadedly engages the inner periphery of spool 4. The spring retainers ill and 12 are biased to a seating position between the casing 7 and the cup 9 respectively for maintaining the neutral position of spool 4. The neutral position is set by rotating the bolt bolt 13 to seat against the end at the spool 4.

The bolt 13 is hollow and receives an adjusting screw 14 which engages a plunger 15 received within the central opening 16 of the spool d. The central opening 16 extends into the spool 4 and defines a valve chamber for receiving the valve element 17 mounted on the valve seat 18 to form a poppet valve 19. The drilled passages 20 and 21 extend radially from the valve chamber 80 and are axially spaced relative to each other and communicate with the annular grooves 22 and 23 respectively. Grooves 22 and 23 selectively receive the detent elements 24 and 25. Detent elements 24 and 25 comprise spherical balls retained in close tolerance holes in sleeve 33 which are positioned between beveled surface 26 and 27 of the collars 28 and 29 respectively. The collars 2t; and 29 are biased by the springs 30 and 31 to maintain a central position of the collars 28 and 29. Spring 31 seats on radial flange 32 of the sleeve 33 while the spring 30 engages a radial flange 34 on the end of housing 6.

The spool 4, of valve 1 is provided with axial passage 35 extending between the cross passage 36 and 6% and to the valve seat ill of the poppet valve 19. These passages transmit fluid pressure from the actuator chambers 37 and 3? to the poppet valve T9. The actuating chambers 37 and 33 are in communication with the fluid actuator 3 through conduits 39 and 4b which in turn are in communication with chambers 41 and 42 of the fluid actuator 3.

The spool 4 defines a plurality of metering grooves 63 and 43 which are misaligned with the pilot passages 44 and 45 respectively. The pilot passage 44 contains a check valve 46 while the pilot passage 45 contains a check valve 47. The pilot passages 44 and 45 extend to communicate with each other through the cross passage 49. Cross passage 49 is connected by the conduit 50 to the compensator 51 of the pump 2.

The pump 2 as shown is a variable volume pump providing pressurized fluid through passage 53 which is in communication with the pressure chamber 54 surrounding the center portion of the spool 4. The pump 2 receives fluid through the inlet conduit 55 from the reservoir 56. Return chambers 57 and 58 are in communication with the return conduits 59 and 60 respectively which return low pressure fluid to the reservoir.

The pump 2 includes a compensator 51 which maintains a residual pressure from the pump of 300 lbs. per square inch when there is no pressure in the pilot passages 44 and 45 and the pilot conduits 49 and 50 as shown in FIG. 1. The pump pressure will normally be maintained at 300 lbs. per square inch above load pressure which is also equal to pilot pressure. The pump includes a built in pressure limiting means which controls the pump pressure to 300 lbs. per square inch above normal operating pressures in the system. For the purpose of illustration the pump pressure will be assumed to be preset at 2300 lbs. per square inch. The peak pressure would limit the maximum pilot line pressure to 2000 lbs. per square inch, since the residual pressure of the pump provided by the compensator of 300 lbs. per square inch and the pilot pressure equal the pump pressure. The poppet valve 19 will be assumed to operate at 2000 lbs. per square inch. These pressures are for the purpose of illustration only and will control the fluid flow from the pump 2 to the hydraulic actuator 3 and operation of the poppet valve and the hydraulically operated detent elements 24 and 25 and will be described subsequently.

Referring to FIG. 2 the detent mechanism is shown in the lower position. The lever is moved to reciprocate the spool in the left-hand direction permitting the detent elements 24 and 25 to drop into the detent groove 23. The collars 28 and 29 cause the detent elements 24 and 25 to drop into the detent groove and maintain a locked position between the sleeve 33 and the spool 4. This position opens the control valve causing pressurized fluid to flow into the chamber 41 and retract piston 65 and its rod relative to the cylinder 66. The spool remains in this position until the end of the stroke and the cycle is complete. Pressure then builds up in chamber 41 as well as in cross port 68 and axial passage 35. The poppet valve 19 then opens permitting pressurized fluid to enter the valve chamber 80. This in turn will force the detent elements 24 and 25 radially outward in their continuing holes from their mating groove 23 to permit the spool again to return to its neutral position in response to the biasing force of the return spring 10.

Referring to FIG. 3 the lift position of the detent mechanism is shown by aligning the detent elements 24 and 25 with the detent groove 22 and permitting the detent element 24 and 25 to be received in the detent groove. The beveled surface 26 and 27 of the collars 28 and 29 bias the detent elements 24 and 25 to be received within the detent groove 22. This in turn locks the spool 4 against axial movement relative to the sleeve 33. This position of the valve remains until the pressurized fluid passing through valve 1 builds up in the chamber 42 of the hydraulic actuator 3. As the pressure builds up, the pressurized fluid is in communication with the cross port 36, builds up in the cross port 36, and follows the axial passage 35 opening the poppet valve 19. The poppet valve 19 permits pressurization of the fluid in valve chamber 80 forcing the detent elements 24 and 25 radially outward and releasing the spool from the sleeve 33. The return spring biases the spool to the normally neutral position as shown in FIG. 1.

Referring to FIG. 4, the float position is shown. The float position is achieved by manually moving the lever 5 and reciprocating the spool 4 in the extreme left-hand position. This aligns the float groove 67 with the detent elements 24 and 25. The biasing of the springs 30 and 31 cause the beveled surfaces 26 and 27 of the collars 28 and 29 to force the detent element 24 and 25 into their mating detent groove. This holds the spool 4 in the position as shown in FIG. 4 in the float position. Pressurized fluid from the source of pressurized fluid 2 does not flow through the valve but remains in chamber 54 at standby pressure. The actuator 3 is free to extend or retract since conduits 39 and 40 are connected to tank thru the valve. In the float position there is no automatic release. The release is accomplished manually by moving the lever 5 to return the spool to its normally neutral position as shown in FIG. 1.

The operation of the device will be described in the following paragraphs.

Referring to FIG. 1 the hydraulic control valve 1 is shown in a normally neutral position. The lever 5 manually controls the position of the spool with relation to the housing 6. When the lever 5 is operated and the spool 4 is moved in the left hand direction, it causes an opening of the valve permitting pressurized fluid to flow from the pump 2 through the chamber 33 to the pressurizing chamber 41 in the actuator 3. Admitting pressurized fluid into chamber 41 retracts the piston 65 and its rod relative to the cylinder 66 which would provide a lowering of the implement. The type of work accomplished by the actuator3 may vary considerably and accordingly for the purpose of illustration we are basically concerned that the actuator 3 extend and completes its work cycle. As the spool is moved in the left-hand direction it reaches a point where the detent elements 24 and 25 are aligned with the detent groove 23. The springs 30 and 31 are biasing the collars 28 and 29 toward each other. The bevel surfaces 26 and 27 of the collars 28 and 29 bias the detents 24 and 25 radially inward to be received with the mating detent groove 23. This in turn locks the spool 4 relative to the sleeve 33 and the control valve 1 remains in the open position supplying pressurized fluid from the pump 2 to the actuator 3. When the actuator has completed its cycle pressure begins to build up in the chamber 41 which in turn produces a build up through the system. The pressure also builds up in the cross port 68 and axial passage 35. When the pressure reaches the predetermined value which was assumed to be for the purpose of illustration, 2000 lbs. per square inch, the poppet valve 19 will open admitting pressurized fluid into the valve chamber to force the detent elements 24 and 25 radially outward against the force of the springs 30 and 31 operating on collars 28 and 29. When the detent elements 24 and 25 are removed from the detent groove 23 the spool 4 is free to return to its neutral position. The return spring 10 biases the spool 4 to return to the neutral position.

When the control valve 1 is moved to the lift position, the lever 5 is operated to move the spool 4 in the right-hand direction. This in turn opens the valve permitting pressurized fluid to flow through the valve chamber 37 to the chamber 42 of the actuator 3. As the chamber 37 is coming into communication with chamber 54 as the spool moves in the right-hand direction the pilot passage 44 and 50 supply pressurized fluid to regulate the stroke of the variable displacement pump 2. The pump is regulated by the compensator 51 as pressurized fluid is admitted through the conduit 50. As the spool is moved in the right-hand direction the detent elements 24 and 25 will seat themselves in the detent groove 22 and lock the spool 4 relative to sleeve 33. This condition exists so long as the spool is manually permitted to remain in this position. When the actuator has completed its cycle the pressure in chamber 42 buildsup which in turn builds up pressure in chamber 37. The increase in pressure in chamber 37 also increases the pressure in the cross port 36 and axial passage 35 which in turn opens the poppet valve 19. When the poppet valve opens pressurized fluid is admitted to the valve chamber 80 and passes through the radial openings 20 to unseat the detent elements 24 and 25 groove 22 and releases spool 4 from the sleeve 33. When this condition exists, the spool is then free to return to its normally neutral position. The return spring 10 will return to the spool to the neutral position as shown in H6. 1.

H6. 4 illustrates the float position of the detent mechanism. The float position is achieved by movement of the spool 4 in the left-hand direction until the detent groove 67 is aligned with the detent elements 24 and 25. In this position, the detent elements are received in the detent groove 67 and the spool is heldin the float position. The spool will remain in this position as long as the spool is not manually removed from this position. The flow of pressurized fluid through the valve 1 is blocked and the hydraulic actuator 3 remains free to extend or retract.

ltis noted that in the lower position when pressurized fluid is being admitted to the chamber 41, the chamber 42 is connected to the opposite side of the valve which in turn permits the flow of the low pressure fluid through the chamber 37, chamber 57 and the return passage 9 to the reservoir 56. When the valve is in the lower position and pressurized fluid is being admitted to chamber d2, the chamber 41 is in communication with chamber 38 and 58 and returns through the conduit 60 to the reservoir 56.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

We claimi l. A hydraulic valve having a detent mechanism comprising, a valve housing means defining valve passage, a spool means reciprocally mounted in said housing for selectively controlling the flow of pressurized fluid from a source of pressurized fluid through said valve passage to a fluid actuator, resilient means in said housing normally returning said spool to a neutral position, a valve biased to a closed position connected to said valve passage for operating in response to a predetermined pressure in said actuator, means defining a chamber intermittently in communication through said valve with said valve passage, detent elements in said housing means, means defining opening'means insaid spool communicating with said chamber for receiving said detent elements and defining at least one operative position of said spool, means biasing said detent elements in engagement with said opening means of said spool and retaining said spool in said position, said detent elements disengaging with said opening means in response to an increase of pressure to a predetermined value from said actuator through said valve and pressurizing said chamber and thereby release of said spool and permit said spool to return to a normally neutral position.

2. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said housing means includes a sleeve in said valve housing means supporting said detent elements for selectively engaging detent opening means in said valve spool.

3. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said valve housing means includes a sleeve for supporting said detentelements and at least one spring biased collar having a beveled surface, said detent elements include spherical balls biased radially inward in response to engagement with said beveled surface on said spring biased collar.

4 A hydraulic valve having a detent mechanism as set forth in claim 3 wherein said detent mechanism includes two spring biased collars biased toward each other to bias said detent elements for engagement with opening means in said spool.

5. A hydraulic valve as set forth and having a detent mechanism as set forth in claim 1 wherein said valve controlling the flow to said chamber consist of a poppet valve carried in said spool.

6. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said spool forms detent opening means defining a hold position when said detent elements are received in said opening means defining the hold position.

7. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said valve biased to a closed position includes a spring and an adjusting screw, said adjusting screw adjustably positions the spring pressure on said valve for presetting the opening pressure at a predetermined value.

8. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said detents comprise spherical balls for reception within the detent o en'in means in said spool.

9. A hydraulic valve and eten mechanism as set forth in claim 1 wherein said spool and housingv define a double acting control valve for a double acting hydraulic actuator, said spool defines two sets at axially spaced detent opening means defining two operative positions for receiving said detent elements.

10. A hydraulic valve having detent mechanisms as set forth in claim 1 wherein said spool and housing means defines a control valve and as said spool includes an adjusting screw for adjusting said resilient means and the neutral position of the spool at said control valve. 

1. A hydraulic valve having a detent mechanism comprising, a valve housing means defining valve passage, a spool means reciprocally mounted in said housing for selectively controlling the flow of pressurized fluid from a source of pressurized fluid through said valve passage to a fluid actuator, resilient means in said housing normally returning said spool to a neutral position, a valve biased to a closed position connected to said valve passage for operating in response to a predetermined pressure in said actuator, means defining a chamber intermittently in communication through said valve with said valve pasSage, detent elements in said housing means, means defining opening means in said spool communicating with said chamber for receiving said detent elements and defining at least one operative position of said spool, means biasing said detent elements in engagement with said opening means of said spool and retaining said spool in said position, said detent elements disengaging with said opening means in response to an increase of pressure to a predetermined value from said actuator through said valve and pressurizing said chamber and thereby release of said spool and permit said spool to return to a normally neutral position.
 2. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said housing means includes a sleeve in said valve housing means supporting said detent elements for selectively engaging detent opening means in said valve spool.
 3. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said valve housing means includes a sleeve for supporting said detent elements and at least one spring biased collar having a beveled surface, said detent elements include spherical balls biased radially inward in response to engagement with said beveled surface on said spring biased collar. 4 A hydraulic valve having a detent mechanism as set forth in claim 3 wherein said detent mechanism includes two spring biased collars biased toward each other to bias said detent elements for engagement with opening means in said spool.
 5. A hydraulic valve as set forth and having a detent mechanism as set forth in claim 1 wherein said valve controlling the flow to said chamber consist of a poppet valve carried in said spool.
 6. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said spool forms detent opening means defining a hold position when said detent elements are received in said opening means defining the hold position.
 7. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said valve biased to a closed position includes a spring and an adjusting screw, said adjusting screw adjustably positions the spring pressure on said valve for presetting the opening pressure at a predetermined value.
 8. A hydraulic valve having a detent mechanism as set forth in claim 1 wherein said detents comprise spherical balls for reception within the detent opening means in said spool.
 9. A hydraulic valve and detent mechanism as set forth in claim 1 wherein said spool and housing define a double acting control valve for a double acting hydraulic actuator, said spool defines two sets at axially spaced detent opening means defining two operative positions for receiving said detent elements.
 10. A hydraulic valve having detent mechanisms as set forth in claim 1 wherein said spool and housing means defines a control valve and as said spool includes an adjusting screw for adjusting said resilient means and the neutral position of the spool at said control valve. 